The behaviour of self-healing materials to undergo automatic repair upon damage without an external intervention has led to increased interest amongst academic and industrial researchers in the last few decades. The conventional and classical constitutive material models have not captured the self-healing phenomenon owing to its complexity. The primary objective of the present work is to model the constitutive response of self-healing materials using continuum damage mechanics (CDM). It can be observed from the available literature that the existing CDM based damage- healing models cannot capture the complete failure of self-healing materials due to inherent assumptions. These models assume that the healed material does not undergo damage or healed material undergoes damage only once. A new variable called the secondary damage variable, capturing damage of healed material, is thus defined to address this drawback, and the fundamentals of damage-healing theory have been rederived. A three-dimensional (3-D) elasto-plastic damage- healing (EPDH) framework based on irreversible thermodynamics has been developed for self- healing materials undergoing isotropic hardening. The proposed implicit damage-healing formulation is numerically implemented using a return mapping algorithm. The proposed EPDH framework is also extended to account for kinematic hardening and implemented using a similar return mapping approach. Another 3-D viscoelastic damage-healing model has been developed for materials like asphalt, which undergo healing in unloading and rest periods. The response of the proposed model has been obtained for multiple strain histories, and detailed parametric studies have been conducted to study the influence of material constants in the evolution equations of damage and healing. The final objective of this work is to build the foundations of damage-healing mechanics, which can be adopted for developing damage-healing models for different self-healing materials.